Ectopic pregnancy has reached epidemic proportions with 70,000 cases per year, with 50 deaths. Fear of ectopic pregnancy results in numerous invasive procedures. Serum B HCG levels and the improved resolution of transvaginal sonography is proving helpful, especially in the earlier diagnosis of an intrauterine gestation. Preliminary studies in 300 patients have shown that simultaneous Doppler can be valuable in these patients. This project proposes to apply these new techniques. Patients will be invited to undergo transvaginal ultrasound (TV US) and transabdominal US. If no fetus is apparent, color TV Doppler will be used to identify the specific flow characteristics of extrauterine trophoblastic and luteal flow. Pulsed Doppler will be used to quantitate Doppler shifts and measure pulsatility indices. Tapes of these signals will be used to derive other quantitative indices to identify specific perfusion parameters of the extrauterine fetus. The results of TA and TV US imaging as we as color and pulsed Doppler will be compared by determining the sensitivity, the specificity, the positive and negative predictive values for each technique and combination of techniques. The anatomic basis for trophoblastic flow is proposed in terms of shunting from high pressure maternal spiral arteries into low pressure, low impedance intervillous spaces, which can be demonstrated histologically. It is proposed to derive a computer simulation of this model to substantiate this hypothesis. these techniques have already proved valuable in preliminary clinical results producing a sensitivity of 80% and a specificity of 60%. The addition of the improved resolution of TV sonography, when added to the tissue characterization made possible by simultaneous Doppler, can only improve these figures. The addition of color should make this a simpler technique for general use in the community and allow an earlier and more accurate diagnosis of ectopic pregnancy. This should not only reduce the mortality but also the numerous laparoscopies and laparotomies.